Last Straw
by cheeseandhamburger
Summary: When L calls the Kira case a waste of time, Light decides to set him straight. Only, he doesn't punch him in the face. He does something else instead. Handcuff period. Spanking!
It was yet another regular day in the Kira investigation headquarters. Misa and Light were having a 'date', with L as a third wheel chained to Light. The world's greatest detective was sad, depressed, and just plain irritated. The case wasn't moving forward, there were no new leads, Kira was killing with impunity as usual, and worst of all he was starting to worry his prime suspect may actually be innocent, or at least not entirely guilty. (Unacceptable!)

And now he was sitting on a couch next to Light, saying that his deduction was maybe, possibly wrong. _Wrong._ L's deductions and the word 'wrong' just didn't fit together. He was the world's three greatest detectives, he just didn't do 'wrong', and yet this time he appeared to have been. At Light's prompting, he had explained his current theory: the real Kira had controlled Misa Amane and Light Yagami into playing the roles of the first and second Kira to make L suspicious of them, and after they were caught their memories were wiped and the killing power was transferred to someone else. If that was the truth then Light, _Light_ who was supposed to be the mastermind behind it all, was somewhat, sort of, possibly (but not necessarily) innocent. As for the real Kira...

"Even if we catch someone under his control," said L somberly, "they'll likely lose their powers and any memory of their crimes, so in the end pursuing them becomes futile."

"But at this point we have no way of knowing if that's the case. Cheer up, would you?"

"Cheer up?" L looked at Light dully. "No, I'm sorry, I can't. It's probably better if I stop trying so hard. By chasing Kira so desperately, we're just putting our lives at risk for nothing. Yes, it's just a waste of time."

There was something very heavy and uncomfortable about the silence that followed this statement.

"Ryuzaki, did you just say that trying to catch Kira is a waste of time?" Light stared incredulously at L.

"That's the gist of it, yes."

"Yay! So you leave Kira alone and Light and I are free, yes?" Misa asked hopefully. She was ignored.

"After everything you've done to catch him," Light asked again, "you're actually saying that giving up is a better option?"

"Precisely," L replied, feeling a strong urge to smirk. It was usually exasperatingly hard to get under Light's skin, and L did try to do that fairly often (for the sake of the investigation, of course). Their enforced closeness gave him plenty of new opportunities to get on his prime suspect's nerves. He deliberately ordered the chain to be made so short they had to share a bed, he interrupted Light's sleep at least two times every night to drag him to the kitchen for a late-night snack, he refused to wait outside the door or even turn around when Light was using the toilet (he needed to keep an eye on him at _all_ times, didn't he?), he forced Light to shower in his full view... The list went on. He tested many subtle and less subtle annoyances to damage Light's control. Angry Kira was far more likely to give something away than a calm one. Sadly, his suspect just wouldn't rise to provocations. He remained polite and composed no matter how hard L tried to taunt him, which was somewhat frustrating.

This time though, Light seemed to finally lose his cool. L's mood improved a little in anticipation. This ought to be interesting.

"You declared war on Kira," Light said slowly, voice low, "you involved innocent people, you put Misa and me behind bars, you've kept us locked up longer than a month, you violated our basic human rights left and right... and now you're telling me it was all for nothing? You're just gonna give up?"

"Really, Yagami-kun," L deadpanned, "you usually catch on a lot faster than this. There is ten percent chance that your time in confinement had significantly lowered your mental faculties. How many more times must I repeat myself before you finally understand?" L reached for a piece of cake Misa had refused earlier, and stopped looking at Light. It was a big mistake.

He was just about to pick up a fork when he was suddenly grabbed from behind. Before he had the time to even register what was going on, he found himself lying face down on Light's lap with Light's legs encasing his own like scissors.

"That's it!"

SMACK!

L yelped, more out of surprise than pain. Then his jean-clad bottom was swatted again, with roughly the same force.

"Light-kun, what do you think you're doing?!"

"Really Ryuzaki, I think it's perfectly obvious. Maybe it's _your_ mental faculties that should be called into question here," Light answered, raining down smacks all the while. Misa watched with wide eyes and mouth forming a large 'o'.

L tried to get up but Light's hand, at least the one that wasn't occupied elsewhere, was pressing his back down.

"Light-kun will desist what he's doing this instant or – AU!" He was interrupted by a particularly vicious smack.

He couldn't believe this was happening. It was completely absurd. L, the world's greatest detective, was getting a _spanking_ from his prime suspect! This wouldn't be tolerated. He would put a stop to this right now!

"Stop? I don't think I will, thanks." Light smiled, continuing his assault on L's upturned posterior. "Judging by your behavior, you need this. Badly."

"This is a violation of-"

"Of what, Ryuzaki? The law? _Your_ human rights?" L could hear the note of smug amusement in Light's voice. "Stay still!"

L didn't stay still. He wiggled trying to get his legs free, but Light only squeezed tighter. This was really disconcerting. He always thought that if push came to shove he would be able to overpower Light due to his capoeira training but he didn't expect getting tackled like this. That, and he might have underestimated his suspect's strength. Plus, his bottom was starting to feel more than a little... uncomfortable.

"Light-kun, this is your last warning," L growled, turning his head to glare at Light. In response, the teen only increased the strength of the smacks.

L yelped. As soon as he was out of this predicament, Light was going to pay.

"I will see Light-kun locked up for this!"

"Will you? Well, in that case I have to make the most of the situation," Light replied and swiftly yanked L's pants down.

Shit.

Wait. Why wasn't the task force doing anything?!

-ooo-

"We have to call the room and stop this!" Red-faced Matsuda reached for the phone.

"Hold on." Aizawa caught his hand. The corners of his mouth were twitching. "There is no hurry."

"W-what?" Matsuda sputtered, looking at the screen. Every member of the task force could see Light holding a madly thrashing figure of L, and fiercely walloping his barely protected (by a pair of pink briefs) bottom. "We have to do something!"

"I don't see why we should." Aizawa looked at the screen with a gleam in his eyes. "If you ask me, the world's brattiest detective had it coming for a good long while." He grinned at Mogi, and the other cop looked like he very much wanted to smile back.

"But-but-" Matsuda stuttered. "That's kind of... not right. He's an adult, you know."

"He sure ain't acting like it."

They all looked at each other.

"Well, I have to admit he wasn't always the easiest person to work with," said Mogi. On the screen, L squeaked as the swats kept falling on his butt. "Admit it."

"He's... not very nice to me," Matsuda said reluctantly. "He always mocks me and calls me an idiot."

Aizawa, who had called Matsuda an idiot on more than one occasion, nodded in agreement. "He may need a good lesson in respect."

Matsuda looked unsure, but nobody disagreed.

-ooo-

L, unable to get out of Light's grip, decided to lie still and quiet, not giving the youngest male Yagami the satisfaction of seeing the spanking get to him. He always believed he had a reasonably high pain tolerance. He could take all the kicks and punches during his fighting lessons fairly well. What was one little spanking in comparison?

Much more than he expected, as he was quickly discovering. Without his jeans, he only had his undies to shield him from Light's surprisingly strong hand. Try as he might, he was unable to stop himself from shrieking in pain (in a manly manner, of course). And worst of all, Light didn't seem to be tiring! He was peppering every square inch of L's bottom with quick, sharp smacks without giving any hint he was planning to stop soon.

"Yagami-kun, stop now and the consequences won't be too severe!"

"Nah. I don't think you've learned your lesson yet," Light replied, and sped up the swats.

"Aiiii!"

"I've put up with the confinement, the handcuffs, and you being an obnoxious, inconsiderate, sadistic prick twenty four hours a day. But you've gone too far this time! You can't just rage-quit the Kira case whenever you feel like it."

"It's," L groaned through his teeth, "my investigation!"

"So this is how little justice means to you? Just a matter of ego? You don't care about solving the case anymore just because I'm not Kira?!"

SLAP, SLAP, SLAP, SLAP, SLAP, SLAP, SLAP!

Light picked up the pace, and L yowled. No matter how much he tried, he just couldn't hold it in. He squirmed pathetically, trying to move his bottom away from the line of fire, but Light just kept on spanking even harder. "Ryuzaki, do you have anything to say to me?" he asked calmly, without interrupting.

"Stoooop! Stooooop!"

"No."

Then, to L's horror, Light pulled down his briefs and landed another terrific smack. With his only protection removed, the detective now felt the full burn of the swats and his eyes watered. It hurt so much more than he expected!

"Aaaaa! Amane-san, say something!" In desperation, he turned to Misa. The model's face was flushed scarlet (but not as scarlet as L's bottom). She was chewing on her lower lip and staring at L's abused butt cheeks.

"Ehm, you have a nice tushie, Ryuzaki!

 _And she calls_ me _a pervert?!_

"You know, Light," Misa giggled, "I didn't know you were into that sort of thing but Misa is open-minded. We could experiment if you like." She batted her eyelashes.

Light only groaned in response, never interrupting the punishment.

With a cry, L hid his face in the cushion, resolving once again to not give a reaction. His resolve withstood about five strict, forceful spanks.

"Help!" he called to the task force and Watari, who surely saw everything through the video feed. He was about ready to admit he couldn't get out of this one without their help. Surely they would save him from this humiliating torment. "Heeelp!"

-ooo-

"Maybe we should help," said Mogi. "There will be hell to pay when this is over if we do nothing."

"You don't have to worry about that, Mogi-san."

The three task force members looked at the gothic _W_ that appeared on one of the screens.

"Watari-san!" Aizawa was surprised. "You're... aware of the situation?"

"Of course." Watari's voice came from the speakers. "I've been watching from the start."

"And you're not doing anything?"

"I considered it at first, but I changed my mind. Ryuzaki is... how should I put it? A little undisciplined."

"A little," Aizawa mouthed with a smirk, nudging Matsuda in the ribs. Matsuda smiled nervously, not looking at the screen where Light's hand kept descending on L's more and more red bottom. L was howling, hitting the couch with his fists, and hurling verbal abuse at Light, which of course changed nothing.

"I may be partially at fault here," Watari said with a sigh. "I was very indulgent with him when he was a child."

"And _only_ then?" Aizawa mouthed again. Usually stoic Mogi snorted.

On the screen, Light raised his knee, giving himself a better access to L's sensitive undercurves.

"You," SPANK, "have," SPANK, "a responsibility!" SPANK.

"EAAAAA! Liiiiight!"

"You need to catch Kira." SPANK, SPANK, SPANK, "and you don't get to," SPANK, SPANK, SPANK, "quit just because your brilliant deduction was wrong," SPANK, SPANK, SPANK, SPANK, SPANK, "and I'm not Kira!"

"Auuu!" L began to bawl in earnest, his struggles growing weaker. Help wasn't coming, and Light Yagami wasn't going to stop until he got what he wanted. "I won't, I won't quit! Light-kun, I wasn't serious! Can't you take a joke?!"

Light answered by unleashing a flurry of spanks that turned L's bottom cherry red.

"It breaks my heart seeing him in this position," Watari assured, "but I can understand where Yagami-kun is coming from. Ryuzaki had put him through a lot, and he can be quite uncaring. This seems a bit harsh," the old man sighed again, "but I think one time over Yagami-kun's lap may just do him some good."

Aizawa nodded in approval. He was willing to test that theory, as long as...

"And you don't need to worry." Watari guessed his thoughts correctly. "Ryuzaki can be petty and childishly vindictive, but I'll make sure he won't cause any... unpleasantness for you or Yagami-kun."

"Waaaaaah! I'm so sorry, Light!" The world's most thoroughly chastised detective wailed, giving up on his pride. He didn't even care about the task force members seeing him like this. He didn't care he was giving the devilish disciplinarian the satisfaction of seeing him beg. He just wanted it to end. "I'm soooorryyyyyy! Please! Pleeease! Waaaah!"

Matsuda looked with pity. L was clearly at his limits, begging like that. His bottom sure looked painful.

L stopped struggling. He just lied there crying pitifully, with Light slapping his bare butt with a slightly less stern expression.

"You will continue the investigation?" he asked.

"Yes! Yes, I promise!"

"And you will let me have at least seven hours of sleep every night?"

"What?! I don't-" SPANK, SPANK, SPANK, SPANK,SPANK! "Waaaaaaaaah! Yes, I will!" L screamed, hoping Light would finally stop now.

"Good, Ryuzaki, good."

L sniffled. Was it over?

"Now just to drive the lesson home." Light said, rising his hand.

"No more, no more, please." L squeaked in terror. "Please, Light, I understand! I understand!"

Light just tripped him up again and finished with a series of about twenty much more severe spanks, ignoring L's soul-wrenching cries of protest. Even after they stopped coming, Ryuzaki was still crying loudly, face flushed and wet with tears and snot.

"It's over," Light said blithely, quickly tugging L's pants back up. L only screamed shrilly, his blistered bottom not taking it well.

"There, you can get up now, Ryuzaki."

L didn't. He kept crying in anguish and humiliation, hiding his face in the now very wet pillow, unable to look his suspect in the eye after what had just happened. Light rolled his eyes, but he allowed the detective to lie across his lap, waiting for him to calm down. Hoping to speed up the process he started to awkwardly pat his back, trying to soothe him.

Suddenly the door opened.

"I was just on the phone with-" Chief Yagami started, but then he looked at the faces of his subordinates. "Is something the matter?"

-ooo-

 **In real life, I only condone spanking between CONSENTING ADULTS. In fanfiction I condone all kinds of spankings.**

 **So, what do you guys think? Okay? Terrible? Made you laugh a little?  
**


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